i got a 2000 GMC Yukon XL 3/4 ton and last night at a drive threw i went to put the drivers window down and when it got about 3/4 of the way down it made a clunking sound so i let go of the button and then when i hit it again to go down it went up, so now the swtich is reversed, press it up and it goes down, press it down and goes up, any thoughts on what it might be? anyone else have this problem?